Improved Methodology for the Preparation of Chiral Amines

More documents

Recommendations

Info

Chiral Pool Compounds Amino acids Hydroxy acids NH 2 Valine COOH phenylalanine NH 2 COOH OH COOH lactic acid OH Ph COOH mandelic acid OH COOH HOOC OH tartaric acid Sugars Terpenes OH OH OH O O HO HO OH OH HO HO glucose mannose OH O camphor geraniol OH Figure 1.3. Examples of Chiral Pool Compounds. Another example utilizing this approach is the synthesis of herbicide (R)-flamprop-isopropyl starting from L-lactic acid. [34] OH COO i Pr (S)-lactic acid MeSO 2 Cl base OSO 2 Me COO i Pr Cl inversion F NH 2 F Cl O N i PrOOC PhCOCl F Cl N H COO i Pr (R)-(-)-flamprop-isopropyl Scheme 1.5.Synthesis of Enantiopure Herbicide from L-lactic acid. 14
1.5.4. Stereoselective Conversion of Prochiral Substrates to Enantiopure Compounds (Asymmetric Synthesis) In asymmetric synthesis a stereogenic centre is created under the influence of some external or internal chiral inducing agents. This strategy can be subdivided into three approaches: substrate-controlled approach; chiral auxiliary approach; and catalyst controlled approach. In substrate controlled approach, chirality is present internally within the molecule directing remaining groups or faces in stereoselective manner. Limitations of this approach come from the fact that enantiopure starting materials are not easily available and the reacting sites should be within close proximity to the chiral centre. Regarding the other two approaches, achiral molecule is converted into chiral entity utilizing either a stoichiometric quantity of the chiral auxiliary or a catalytic quantity of chiral catalysts. In the chiral auxiliary approach, chirality is induced in achiral molecule utilizing external chiral entity through forming covalent bond with the achiral starting material. This auxiliary is then cleaved from the final product in an additional step. Special precautions should be taken to avoid any racemisation of the final product in the deportation step. One example of this auxiliary approach is shown in scheme 1.6 in which (1S,2S)-(+)- pseudoephedrine is used as the chiral auxiliary to produce diastereomeric alkylated pseudoephedrine amides which can form enantioenriched carboxylic acids(by hydrolysis), alcohols and aldehydes (by reduction). [35] 15
Page 1 and 2: Improved Methodology for the Prepar
Page 3 and 4: This dissertation is dedicated to a
Page 5 and 6: suppressing alcohol formation and p
Page 7 and 8: Prof. Mohamed El-Azizi, Prof. Abdel
Page 9 and 10: Et EtOH EtOAc GC h HPLC HRMS Hz J K
Page 11 and 12: Table of Contents Abstract. Acknowl
Page 13 and 14: 4.1.5. Synthesis of Emitine 85 4.1.
Page 15 and 16: Chapter 1 Introduction 1.1. Chiral
Page 17 and 18: 1. Cis-trans or geometric isomers.
Page 19 and 20: O O O * NH Thalidomide (R)-active a
Page 21 and 22: One enantiomer may be responsible f
Page 23 and 24: 1.5.1. Synthesis of Enantiomericall
Page 25 and 26: 1.5.2.2. Kinetic Resolution Kinetic
Page 27: compound by the auxiliary. The auxi
Page 31 and 32: It is estimated that 3000 tonnes (a
Page 33 and 34: k R R P 1 k rac S k S P 2 Figure 1.
Page 35 and 36: (S)-(α)-Methylbenzylamine and its
Page 37 and 38: fourth chapter showing different dr
Page 39 and 40: Burk was successful in reducing ary
Page 41 and 42: Table 1.1 Rhodium Catalyzed Reducti
Page 43 and 44: [8] E. L. Eliel, S. H. Wilen, Stere
Page 45 and 46: [42] a) J. Blacker, Innovations in
Page 47 and 48: [67] a) H. Qin, N. Yamagiwa, S. Mat
Page 49 and 50: of imine reduction in the past eigh
Page 51 and 52: 8 years beginning from the year 200
Page 53 and 54: 2.2.3. Nguyen Special Substrates. A
Page 55 and 56: Figure 2.4 General Catalyst structu
Page 57 and 58: 2.3.2. Different Substrates Categor
Page 59 and 60: H 2 , toluene, 25 °C, 4 h an ee of
Page 61 and 62: 1). They described the role of each
Page 63 and 64: More recently, 2008, he described t
Page 65 and 66: [22] E. Guiu, M. Aghmiz, Y. Diaz, C
Page 67 and 68: Chapter 3 Reductive Amination 3.1.
Page 69 and 70: . CH 3 CO(CH 2 ) 5 CH 3 H 2 NCH 2 C
Page 71 and 72: superior in terms of conversion (89
Page 73 and 74: O NHR 3 R 4 R 4 R 3 N OTi(O i Pr) 3
Page 75 and 76: Scheme 3.9. Synthesis of (S)-Metola
Page 77 and 78: groups decreased both the enantiose
Page 79 and 80:
progress of the reaction was monito
Page 81 and 82:
attempts were directed for the asym
Page 83 and 84:
hydrogen bonding, is chiral and its
Page 85 and 86:
Later he utilized this methodology
Page 87 and 88:
OMe OMe O HN HN HN O 2 N 71 % yield
Page 89 and 90:
compared to the oil refinery indust
Page 91 and 92:
[14] V. I. Tararov, R. Kadyrov, T.H
Page 93 and 94:
[55] a) R. Kadyrov, T. H. Riermeier
Page 95 and 96:
Chapter 4 Drugs and Reductive Amina
Page 97 and 98:
Scheme 4.2. Synthesis of Muraglitaz
Page 99 and 100:
Studies showed that the active isom
Page 101 and 102:
aminoacid producing the protected a
Page 103 and 104:
O NH 2 1. p-TsOH/toluene 2. BH 3 -T
Page 105 and 106:
O O 125 NH 2 a 93% O O 126 H Bu N T
Page 107 and 108:
ethyl carbamate by acylation with e
Page 109 and 110:
4.1.16. Synthesis of Ritonavir and
Page 111 and 112:
4.2. Conclusion Different important
Page 113 and 114:
Chapter 5 Stoichiometric Use of Ytt
Page 115 and 116:
The unique feature of this methodol
Page 117 and 118:
Ytterbium triflate is the most comm
Page 119 and 120:
Ruthenium(III) chloride 31.7 4 4.2
Page 121 and 122:
t-Butyl methyl ether 15 - - 82 Hexa
Page 123 and 124:
2-octanone starting material. When
Page 125 and 126:
3 Yb(OTf) 3 d 4 Ti(O i Pr) 4 e 5 B(
Page 127 and 128:
If a [1,3]-proton shift of the init
Page 129 and 130:
enhanced stereoselectivity. For exa
Page 131 and 132:
WO2006030017, 2006; c) T. C. Nugent
Page 133 and 134:
4 60 86 5 50 86 6 40 84 7 20 79 8 2
Page 135 and 136:
The reactions described above all u
Page 137 and 138:
e.g. compare entries 1, 5, 6, and 9
Page 139 and 140:
solvent in the stoichiometric and c
Page 141 and 142:
[2] Farina, V.; Grozinger, K.; Mül
Page 143 and 144:
congested which should be favored.
Page 145 and 146:
imine area % (GC analysis) time (mi
Page 147 and 148:
Inversion at the nitrogen atom of t
Page 149 and 150:
anti-6) would be expected to have m
Page 151 and 152:
e.g. AcOH, suppresses alcohol by-pr
Page 153 and 154:
eductive amination of a prochiral k
Page 155 and 156:
Appendix Experimental Section Gener
Page 157 and 158:
and the mixture was stirred for 30
Page 159 and 160:
Reaction details: Yb(OAc) 3 (1.1 eq
Page 161 and 162:
etention time [min]: major (S,S)-2b
Page 163 and 164:
time [min]: major (S,S)-2c isomer,
Page 165 and 166:
obtain the hydrochloride salt (0.41
Page 167 and 168:
with etheral HCl provided the hydro
Page 169 and 170:
Research experience: Date Project S
show all

Improved Methodology for the Preparation of Chiral Amines

You also want an ePaper? Increase the reach of your titles

Delete template?

Save as template?